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Re: LC 520/550 and Color Classic (Rom Slot Addition)

I asked Warren (bomarc) the same question, but in regards to the the Color Classic because i knew he didn't have a LC520 or LC550 schematics to look at.witch is missing the same parts but in different locations.

OK, first off, I am NOT an engineer, and 90% of what you said is total gibberish to ma, as I don't speak computese, I don't even know where the power cord goes on one. With this in mind, I took a look at the print, and found the unpopulated area you mentioned, and am going to assume you are wanting to replace the missing parts, no??? I also got a wild hair up my old wrinkled ass and went through my other Apple prints looking for a similar configuration, no no avail, so this is something new - - to me anyway. The transistors are most likely simple switching types, and most likely surface mount bastards as well. If so, I would guess they would have used MMBT3904 for Q2 (top mark 1AM) and MMBT3906 for Q3 (top mark 2A). I am to antiquated to mess with surface mount and would use their thru-hole counterparts, namely 2N3904, and 2N3906. I have replaced these things by bending a tiny "L" at the ends of the leads, and carefully ( VERY VERY CAREFULLY) soldering these to the correct pads. Basing on the SMD part looking at them with the single tit up, is bottom left tit - Base, Top tit collector, and bottom right tit - emitter. Basing on the TO-92 package thru-hole looking at the flat face is Emitter, Base, Collector. Of course, you kNOW all this already I trove. As for the resistors, I don't know. Usual rule of thumb is base bias resistor ten times collector load resistor, so using base bias resistor of 10K, the collector load would be 1K. This thing uses a collector load on Q3 of two resistors to two different B+ levels, so ?????????? I would advise you to call Apple, but the we BOTH know what secretive shitwipes THEY are. Find an engineer and present the problem to him for better results.